dyno-max mufflers good / bad?

I have a pair of TTIs dynomaxes in full 3 inch on a 425hp, 360. Theyre 15 yrs old now. no rust. Like poster #7 says. When I put the Gear Vendor in, I had to lose the H-pipe. Lost some torque on that. Took a lot of fooling around with jets and timing to get some/most of it back.
-I used to take the 360 out every fall, and put a stock C/R, 1973, 318-4v,A/T, into it for the winter. Thats full 3 inch duals with H-pipe. Man that 318 sounded good. Sometimes I think about putting it back in......Problynot.